1. Field of the Invention
The present invention relates to microwave devices. More specifically, the present invention relates to variable attenuators used in microwave systems.
While the present invention is described herein with reference to a particular embodiment for an illustrative application, it is understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications and embodiments within the scope thereof.
2. Description of the Related Art
Fixed and variable microwave attenuators provide gain level adjustments for microwave circuits and systems. Commercially available coaxial variable attenuators are large and heavy because their operation requires a relatively long adjustable length of lossy center conductor.
Further, the low performance to weight ratios of conventional variable attenuators limit their practical utility in space applications. Attempts to reduce the size and weight of conventional variable attenuators has resulted in designs having unacceptable performance. As a result, fixed attenuators have been used more often for spacecraft applications.
The use of fixed attenuators, however, is also problematic. For example, it is not known in advance which mix of attenuators is needed for the radiated power and gain requirements of a given system. It is generally necessary, therefore, to have on hand a large number of attenuators. The retention of a sufficient number of attenuators of various ranges often necessitates a large and costly inventory. In addition, a time consuming and costly trial and error method of design is required during which many iterations of different attenuation settings are tried before a final value is determined. It is apparent that a variable attenuator for such applications would be highly desirable.
There is therefore a recognized need in the art for a small, lightweight, inexpensive, high performance variable attenuator suitable for spacecraft systems and other applications demanding high performance to size and weight ratios.